Early season salmon fishing off the coasts of California and most of Oregon was shut down Wednesday by federal regulators responding to an unprecedented collapse of salmon populations along the West Coast.

The actions affect commercial and recreational fishing seasons either under way or scheduled to open in the coming weeks. When they meet again next month, regulators are likely to close the bigger fishing seasons that come later in the year.

Specifically, a small recreational fishing season off Fort Bragg that opened in mid-February will close April 1. Other recreational fishing seasons from San Francisco to the Mexican border that were scheduled to open April 5 have been closed.

Commercial fishing that was scheduled to open off Fort Bragg on April 7 was also closed.

In Oregon, the start of recreational and commercial seasons that were set to open March 15 were delayed to April 15, but it appears likely those seasons will be closed when the Pacific Fishery Management Council meets again in early April.

The actions were in response to major declines in salmon populations that were especially pronounced in the Sacramento River fall run of chinook salmon, which produced more than 80 percent of the salmon caught off the California coast.

Last year’s return of spawning adults was less than 90,000, the second lowest figure on record. Worse, the number of returning 2-year-olds — a key predictor of the 2008 return — was a record low, meaning this year is likely to be much worse.

On Tuesday, scientists informed the council that even without any salmon fishing at all, the return of the Sacramento River fall run was expected to be fewer than 60,000, or less than half the minimum target set by regulations.

“There’s not going to be any fisheries this year that have any impacts on the Central Valley run,” said Duncan MacLean, a commercial salmon fisherman from Half Moon Bay and the industry’s California representative to the council.

“I’m totally disgusted,” he added. “I am sick and tired of putting myself and my family through this.”

Agency scientists for the most part have blamed a shift in ocean conditions along the West Coast for the problems. But others, including the head of the fishery management council, contend that shift cannot account for the severity of the problem with Sacramento River salmon.

MacLean and many other anglers blame the problem instead on water management in the Delta and throughout the Central Valley.

“This is like going to debtors prison for your father’s sins,” MacLean said. “This is working its way up the food chain. It started with the Delta smelt (which appears to be close to extinction) and it’s working its way up.”